Device for indicating deflation of pneumatic tires



NOV. 8; 1938. P M BQURDON 2,136,038

DEVICE FOR vINDICATING DEFLATION OF PNEUMATIC TIRES Filed May e, 1957 2 sheets-sheet 1 95 v11 114 10.4 105 110 Z 1Z0 INVENTOR flaw /larlvun/a/v ATTORNEYS NOV. 8, 1938, I P, M BOURBON 2,136,038

DEVICE FOR INDICATING DEFLATION OF PNEUMATIC TIRES Filed May 6, 1937 2 Sheets-Sheet 2 1 .4 [if f INVENTOR Patented Nov. 8, 1938 UNITED STATES PATENT OFFICE DEVCE FOR INDICATING DEFLATION OF PNEUMATIC TIRES Pierre Marcel Bourdon, Paris, France, assignor to Michelin & Cie, Clermont-Ferrand, France, a corporation of France Application May 6, 1937, Serial No. 141,027 In France May 7, 1936 12 Claims. (Cl. 116-34) This invention relates to devices for automatiinternal pressure upon inflation of the tire to cally indicating when the air pressure in apneuallow air to ilo-w in but one direction there- Inatic tire falls below a predetermined minimum. through. Associated with this valve is a similar As is well known, tires may be seriously damvalve having a diaphragm through which air may aged by running them below their optimum presbe passed from the inlet stem to the inner tube 5 sure as wellas continuing to run on punctured and which acts under normal conditions as a tiresdvwhile` they are deflating. In a vehicle having check valve preventing return of air from the but a single tire to the wheel, a reduction below inner tube tothe inlet stern and the valve assothe best operating pressure will cause unnecesciated therewith. The diaphgram valves are so 1,0 Sary flexing of the tire casing,resulting in side related in the device that when pressures exerted Wall cuts and breaks and cracking and separatby the air in the tire falls below a predetermined ing of the plies in the tire, thereby greatly reducminimum, the air is by-passed to a sound making ing its mileage life. device consisting of a vibratable diaphragm valve Truck tires likewise are subject to deterioraand thence to a horn for rendering the sound iml5Y tion upon reduction of pressure below their optipulses audible. 15 mum operating pressures. In addition, when a. One of these devices may be used in conjuncplurality of tires are used on a single wheel they tion with each tire on a motor or other vehicle are subject to blo-wing out when loss of pressure having pneumatic. tires and likewise they may in one of the tires places a greater load on the be connected in parallel when used with multiple 20, other tires. tire wheels in order to indicate when one of the An object of the present invention is to provide tires is partially deated. a device or a plurality of such devices to be con- Suitable means may also be providedfor connected to tires during service and which givean necting the parallelly arranged sound making unmistakable warning when the pressure deldevices between the multiple tires so that the creases in the tires. pressures therein are equalized and tending to 25 A further object of the invention is to provide a retain them in equilibrium so long as the presdevice which may be installed on a vehicle wheel sure in one does not fall below a predetermined and connected to a tire tube and which acts, upon minimum pressure. deation or partial deation of the tube, to give Devices embodying my invention may be mount- 3,0 an audible Warning. ed either directly on the valve stem for rotation A still further object of the invention is to pro- With. the Wheel 01 they may be mounted at the vide a warning device which may be used in concenter of the wheel and connected through suitl junction with multiple tire wheels serving both able means to a sound making device carried on as a connecting means between the tubes for the interior of the car so that the driver will hear 'da equalizing the pressures therein when above a the warning Signal This last CODSTUC'UOII iS 35 predetermined minimum pressure and giving a, particularly suitable for use with trucks which warning signal when the pressure in any of said cause a great deal of noise and also with pastires decreases Suvieiently to exceed a, predetersenger vehicles having sound insulated bodies. mined differential in pressure. For a, better understanding of the present in- 4Q One form of the invention may consist of a, vention, reference may be had to the accom- 40 housing containing elements connectible to the panying drawings. in which: valve stem of an inner tube andhaving a similar Figure l is a side view of one form of a device stern which may be connected to the ordinary embodying the invention suitable for attachment air dispensing device for filling or inating the directly to the valve stem of an inner tube and 45., tires. Between these two connections may be a rotatable with the wheel, the device being shown plurality of diaphragm type valves which norpartly in section to; show the details thereof;

mally prevent flow of air from the tube outwardly Figure 2 is a sectional View taken on line 2 2 through the filling stem. The valves are so conof Figure 1; structed and arranged that they direct outward- Figure 3 is a side View of a vehicle wheel and ly flowing air toa sound making device when the tire showing the form of invention disclosed in 50 pressures on the valves are decreased below a Figure 1 attached to the valve stem of the inner predetermined amount. tube;

More specically, one form of the invention Figure *4 is a sectional view of a modified form may include, an air inlet stem having a diaphragm of the invention of a type suitable for mounting 55, valve which may be subjected to external and at the center of the wheel;

from the diaphragm 38.

Figure 5 is a side view partly in section of a portion of the device disclosed in Figure 4; and

Figure 6 is a diagrammatic showing of one form of the invention as applied to multiple tire wheels.

Illustrative of one form of the invention, Figures l, 2 and 3 disclose a warning signal device I0, attachable to the valve stem of a pneumatic tire as best shown in Figure 3. The warning signal Il) consists of several associated elements including: an air inlet valve and chamber construction A; an air escape valve B; a sounding device C; an air outlet valve and chamber D connectible to a valve stem; and a setting device E. The several devices A, B, C, D and E are connected through and mounted on a cylindrical casing I2. The air inlet valve A is mounted in bore I4 of the laterally projecting housing I6. The housing I6 forms the chamber for the air inlet mechanism A which consists of a stem I8 having a disc-like collar 28 thereon. The collar is retained against a gasket 22 mounted at one end of the bore I4 in airtight relation by means of an internally threaded collar 24.

The stem I8 communicates with the bore I 4 through an inlet passage 26 having an angular extension 23 opening to the exterior of the stein. The stem is also provided with an axial bore 38 having an angular passage 32 communicating with the exterior of the tube opposite the opening 28.

A diaphragm consisting of a rubber sleeve 34 is slipped over the inner end of the stem I8 and clamped in any suitable manner around the stem at points spaced from the outlets 28 and 32. When airis forced into the stem from the air hose of an air supply, the diaphragm sleeve 34 is stretched allowing air to pass around the stem from outlet 28 into lateral bore 32 and thence out of the bore into the chamber formed by the lO transverse bore I4.

rihe above described construction forms the air inlet device A.

At the opposite end of the bore I4 is a chamber 36 of greater diameter in which is mounted a rubber dis-c diaphragm 38 normally urged in the direction of the inlet stem I8 by means of a spring 40 acting against the cup-shaped sleeve 42 slid-V ably mounted in annular gaskets 44 xed in the enlarged portion of the bore 36, and retaining the edges of the diaphragm 38 in position in the housing l5. The cup-shaped sleeve 42 bears against the diaphragm 36 and normally holds it in plane condition. The tension on the spring 46 may be adjusted by means of a cup-shaped member 46 opening toward the diaphragm and having threads 48 on its edges engaging similar threads on the interior walls of the chamber 36 to allow it to be adjusted towards and' from the diaphragm.

rEhe right-hand end of the chamber 36 may be closed by means of a cap having a threaded rim and also having acentrally located cylindrical sleeve 52 in which is received a threaded rod 54, the end of the rod normally being spaced slightly The diaphragm 38 is also provided with a central perforation 56 in alignment with the rod 54, which acts in conjunction with the end of the rod as a valve preventing ow of air therethrough when the presn sure on the inlet side of the diaphragm becomes suiciently great, and opening to allow escape of air when the pressure in the chamber I4 decreases to a predetermined value. Communicating with the chamber 36 between the cup-shaped elements 46, i2 is an outlet 58 through which air may be exhausted to atmosphere.

The above described construction forms the air escape valve and chamber B.

In operation, when air is forced through the inlet nozzle I8, it passes along the passage 26, expands the diaphragm 34 and passes out through the outlet 3B increasing the pressure in the chamber between the diaphragm 38 and the nozzle I8. Air will leak out through aperture 56 in the disc diaphragm38 until the pressure in the chamber reaches a predetermined value. The diaphragm 38 will be then forced against the end of the rod 54, closing the aperture 56. Air will then pass from the bore I4 through the passageway 60 into the cylinder` I2, building up the pressure therein.V

The cylindrical member I2 is closed at its righthand end as viewed in Figure 1, by means of suitable locking rings and gaskets 62 which also support a centrally located tube 64 and diaphragm hereinafter described, forming the sound making device C.

As the air passes into the cylinder I2, the pressure therein will build up and the air escapes through passageway 66 in the tube 64 under the rubber diaphragm 68 and intothe passage 'I0 and thence through the bore 'i2 to the connection 'i4 which may be threaded into the valve stem of an inner tube, this construction forming the outlet valve D.

The valve D may be provided with a xed concentric rod 'I6 mounted on a spider I8 disposed in the connection i4 for depressing the valve stem in an inner tube to allow direc-t communication between the inner tube and the chamber 30 surrounding the diaphragm 68 formed in a reduced extension of cylinder I2 and separated therefrom by a partition 8l. There is no direct communication between the chamber 80 and the interior of cylinder I2 except through passages 66, 'l0 and 12, so that the pressure in the .chamber 80 will be substantially equal to the pressure in the tire and normally slightly less than the pressure in cylinder i2. The passage 'I2 in the tube 64 is pro-vided with a laterally opening portion 82 which is normally closed by a heavy rubber diaphragm 84 encircling the tube 64. An inclinedpassageway 86 of larger cross-sectional area communicates with an axial bore 88 opening into a horn 90 xed in the end of cylinder I2 through which the warning signal is given. When the tire tube is fully inated, the chamber between cylinder I2 and tube 64, the chamber I 4 between the diaphragm 38 and the inlet stem I8 and the tube contain air at substantially equal pressures.

When the pressure in the inner tube decreases, the pressure in chamber 86 likewise decreases. The pressure in the cylinder I2 therefore is greater than the pressure in chamber 80 and will tend to distend the diaphragm 68 to allow air to pass from the cylinder I2 into the chamber 8U; when the pressure in the cylinder I2 drops suiciently, the pressure in chamber I4 will likewise drop and allow the diaphragm 38 to move away from the rod 54, permitting the air in the cylinder I2 and chamber I4 to escape through the outlet 58 to atmosphere. When the pressure in cylinder I2 drops suiiciently, the pressure in the tire tube will be suflicient to act through passage 'I2 to expand the diaphragm 84. The air from the inner tube will pass around the tube 64 and exhaust through the passageways 86 and 88. Since these passages are of greater diameter than the passage 12, theyV will more quickly exhaust the air than passage 'I2 can supply it, and the diaphragm will againseal the openings, giving a sound impulse. This expansion and contraction of the diaphragm will take place at audible frequency vibrating the column of air in passage 88 and producing a sound so long as the pressure in the tire tube and passage 12 and 82 is sufficient to expand the diaphragm. rIhe duration of the period of vibration of the diaphragm may amount to about thirty seconds after which the diaphragm 84 will seal the passage 82 and no further deflation of the tire can take place through the sound making apparatus.

When it is desired to replace the tire, the device l may be unscrewed from the valve stern of the deflated tire, the deflated tire removed, an inated tire placed on the wheel and the sound making device again screwed into the valve stem. However, the pressure in the warning device at this stage is not in equilibrium with the pressure in the tire. The pressure in the tire tube is greater than the air pressure in cylinder |2, thereby allowing the diaphragm 84 of the sound making device C to vibrate, and also allowing leakage of air from the tire. To prevent leakage of air from the tire, the setting device E is used during attachment of the device i0 to the tire. The setting device consists of a small housing 02 fixed to the cylinder I2 and having passagesr 94 and 96 communicating with the chamber 80 and the interior ofthe cylinder |2 respectively. These passages 94 and 96 communicate with longitudinal chambers 98 and |00 respectively in the casing 92 and having their cuter ends closed by means of suitable threaded caps |02 and |04. The chamber 98 encloses a spring |06 normally urging a valve |08 into engagement with a valve seat ||0 on a partition between the chambers 98 and |00. 'I'he partition is provided with an aperture ||2 through which passes the stem ||4 of the valve |00 with sufcient clearance to permit passage of air therethrough. The valve is actuated by means of a button ||6 mounted slidably in the cap |04 and having disc-end |l'8 thereon bearing against an air-tight rubber diaphragm |20 between the valve stem 4 and the push button disc ||8. When the button ||6 is pushed to the left, as viewed in Figure the valve stem is pushed to the left against the spring |06. unseating the valve |08 allowing air in the tire tube to ilow through passage 94, chamber 98, chamber |00 and passage 96 into the cylinder |2, bore I4.

and closing the diaphragm valve 38, thereby equalizing the pressures throughout the device and setting it for future operation when and if ithe tire should become deflated,

Another form of the invention which may be permanently mounted on the wheel to form a part thereof, is disclosed in Figures 4 and 5. This construction is similar in its method of operation to that described, but instead of being mounted on the valve stem is supported at the end of the axle or replaces a hub cap and is used when it is desired to place in the interior of the car the sound making device which, if desired, may be replaced by any suitable warning device operable by the compressed air escaping from the inner tube. In this construction, the inlet valve A, the air escape valve B, the air outlet valve D, the setting device E, and a valve F cutting off the sound making device C or other warning device `operable by compressed air and placed in the interior of the car, are mounted in a hexagonal casing |30. In this form of the invention, the valve inlet stem |32 is provided with a rubber diaphragm valve |34 and communicates through passage |36 celtes with the passages in valve |54 through passage |55. The outlet passage |56 of the valve F communicates with an axial bore or passage |58 connected through suitable tubing to the sound making device or other warning device placed in the interior of the car. Alsocommunicating with chamber |38 of air escape valve B and the chamber |52 of the cut off valve F through passages |60 and |62 is the setting device E;

In this construction, when it is desired to fill a tire, air is forced through the inlet nozzle |32 through the diaphragm valve |34 to the air exhaust valve chamber |38 where the air can escape through the aperture |64 in diaphragm |40 to atmosphere until a suicient pressure is' built up in the chamber |38 to cause closing of the aperture |64. The air then passes through passageway |42 through the diaphragm valve |44 in the chamber |46 and through nozzle |48 and suitable tubing having means for depressing a valve in a valve stem to the inner tube, inflating it. Likewise, air passes through a passageway |50 into the chamber |52 to equalize the pressures on opposite sides of diaphragm |68 of cut off valve F.

Upon leakage of air from the inner tube and a consequent decreasev inpressure in chamber |46, air will pass from the chamber |52 around the diaphragm valve toward the tire until the pressure in chamber |52, passage |42 and disc diaphragm chamber |38 decreases sufficiently for the aperture |64 to be opened, whereupon air will escape from the `chamber |52 of valve F to atmosphere. 'I'he air from the inner tube will then pass through chamber |46 through passageway |55 into the axial passages in valve F and then through axial bore |58 to a warning device which may be a noise making device similar to device C described in connection with Figure 1. The air escaping from the inner tube through valve 44, valve F and axial bore |58 is transmitted to the noise making device or other warning device inthe interior of the car throughv a suitable construction such as that shown in Figure connecting the vehicle body and the rotating wheel.

As shown in Figure 5, the passage |58 extends through a tubular extension |10 having a bearing sleeve |12 retained thereon by a locknut and washer |14. Rotatably mounted on the bearing sleeve |12 is' a cup-shaped sleeve |16 carrying at its outer end in xed relationship thereto, a housing |18 having a stem |80 thereonV which may be connected through suitable tubing to a horn in the interior of the vehicle. The housing |18 is provided with a passage |82 communicating with a chamber |84 between the sleeve |16 and the housing |18. Sleeve |16 is provided with a passageway |86 therethrough communicating with a chamber |88 between the end of sleeve |16 and the end of the tubular extension |10. The chamber |88 is thus in communication with the passageway |58, so that the sound impulses may pass from the passageway |58 through chamber |88, passage |86, chamber |84, to the passage |82 of the housing member.

The sleeve |16 is rotatable on the bearing sleeve |12 and is retained in airtight and oiltight relationship thereto by means of suitable gaskets |90 and a ring ange |92 fixed to the end of the, housing member |30. This construction permits ready rotation of the housing |30 with the wheel while allowing the housing |80 to be stationarily connected to the sound making device in the interior of the vehicle.

Constructions similar to those above described may also be utilized in conjunction with multiple tire wheels, as best shown in Figure 6, 'This construction includes the air inlet stem 200 of air inlet device A connected through diaphragm valves 202 to pressure chambers, only one of which will be described since theyare identical, and a sound making device. The diaphragm valve 202 communicates with the chamber 204 having at one side the disc diaphragm valve 206 of air escape valve B through which the air may temporarily escape until pressure builds up in the chamber 204. The air in chamber 204, upon closing the diaphragm valve 206, will pass through the diaphragm valve 208 of air outlet' device D into the tire 2|0 through the passageways 2|2. The valve stem of the `tirer 2|!) is also in direct communication with the diaphragm valve 2|4 in the pressure chamber 204 and has one branch 2|6 thereof communicating with the sound making device 220, corresponding to a sound making device C of the type above described.

Also, a setting device 222 above described, communicates directly with the tire tube 2|0 and the chamber 204.

In order to equalize the pressure between the two tires, branch pipes are provided connecting the interiors of the tires 2|0. These branch pipes 224 have lateral orifices 226 and 22B and their ends are separated by a partition 230. A relatively non-resilient, diaphragm 232 normally seals the orices 226 and 228 but is expansible when sufficient pressure is exerted through one of the pipes 224. The resiliency of the diaphragm 232 determines the minimum pressure which will remain in either of the tires if one of them should become deflated. By increasing or decreasing the resilience of the diaphragm 232, it is possible to allow communicationY between the tires when the pressure in both is above a predetermined minimum value, and also to seal one tire from the other when the pressures in both decrease to such an extentY that the diaphragm closes the orifices 226 and/or 228.

With the `above construction, if one of the tires deflates, air can leak through diaphragm valve 208 from chamber 204 until the disc diaphragm valve 206 opens, whereupon the chamber 204 will lose its pressure and the air can pass directly from the partially deflated tire to the sound makingV device 220, thereby indicating that one of the tires is deiiated.

The setting devices 222 are used when'it is desired to replace a deated tire with an inflated one in the manner described above.

It will be understood that the device disclosed in Figures 1 and 2 may be used in conjunction with one or more tires when connected in parallel in the manner disclosed in Figure 6 and likewise the form of the device disclosed in Figures 4 and 5 may with equal facility be used for multiple tire wheels.

It will also be understood that there Amay be many modifications made in the specific construction of the preferred forms of these devices without departing from the invention. Therefore, the modifications given should be considered illustrative and not as limiting the scope of the invention as dened in the following claims.

I claim:

`1. In a signalling device for indicating the deflation of pneumatic tires, the combination of an air inlet valve, an air outlet valve, separate chambers surrounding said valves, warning means comprising a vibratory diaphragm, a chamber surrounding said diaphragm and communicating with the air inlet and air outlet chambers, said outlet valve allowing flow of air from said warning device chamber to said air outlet valve chamber only, means for allowing escape of air from said warning means chamber when the pressure in said chamber drops below a predetermined mini mum, and a member having therein two passageways of different cross-sectional areas cooperating with said diaphragm and communicating with the air outlet valve chamber for allowing passage of air from the tire tube to vibrate said diaphragm when the pressure in said warning device chamber drops below the pressure in the air outlet chamber.

2, The signalling device set forth in claim l, comprising an auxiliary chamber communicating with the air outlet chamber and the warning means chamber, and a manually operable valve in said auxiliary chamber allowing air to flow from the air outlet chamber to said warning means chamber.

3. In a signalling device for indicating deation of pneumatic tir-es, the combination of a sounding device comprising a chamber and a vibratory diaphragm in said chamber, means connecting the interior of the chamber to the interior of a tire tube to allow gas to pass only from said chamber to said tire tube and for normally maintaining the gas pressure in the cham- Vber at least as great as the pressure in the tire tube, means for decreasing the pressure in the chamber to less than the pressure in the tire tube when the pressure in the latter falls below a predetermined minimum, and` a member having passageways of different cross-sectional area cooperating with said diaphragm and communicating with the tire tube to deliver gas to vibrate said diaphragm when the pressure in the chamber is sodecreased.

4. The signalling device set forth in claim 3, in which the means for decreasing the pressure in thev chamber comprises a perforate diaphragm and means for closing the perforation when the gas pressure on the perforate diaphragm exceeds a predetermined minimum.

5. The signalling device set forth in claim 3, comprising a member having a passageway connecting the tire tube with the chamber, and a valve manually operable to allow gas to pass from said tube to said chamber.

6. The signalling device set forth in claim 3, comprising a stationary horn, and means communicating with the vibratory diaphragm to deliver the vibrations to said horn to produce a sound.

'7. In a signalling device for indicating deflation of pneumatic tires, the combination of a warning device comprising a chamber and a vibratory diaphragm having one surface exposed in said chamber, means for delivering gas under pressure to said chamber and to a tire tube, a member having a first passageway for delivering gas from the tire tube against another surface of said diaphragm and a second passageway of greater cross-sectional area for exhausting the gas delivered by the first passageway, the gas pressure in the chamber being normally at least as great as the gas pressure in the tire tube and retaining the diaphragm static, means for decreasing the pressure in the chamber to less than the pressure in the tire tube when the pressure in the latter falls below a predetermined minimum to allow the gas to pass through the said first and second passageways and vibrate the diaphragm.

8. The signalling device set forth in claim 7, including a setting device for equalizing the pressures in the chamber and the tire tube comprising a member having a passageway therein communicating with the tire vtube and the chamber and a manually actuated valve in said member normally closing said passageway.

9. In combination with a vehicle having multiple tire Wheels, a signalling device comprising a vibratory diaphragm, a member having therein a first passage delivering air under pressure against said diaphragm, and a second passage of larger cross-section than the rst passage for allowing escape of air delivered against the diaphragm whereby iiow of air from the first passage into the second passage'will cause the diaphragm to vibrate, and pressure controlled valves connecting the sounding device toV the tire tubes, whereby decrease in pressure of the gas in any of said tubes will open the associated valve to deliver air through the rst passageway to vibrate said diaphragm at audible frequency.

10. The combination set forth in claim 9, comprising a conduit connecting the tubes, a pressure controlled valve in said conduit operable by the gas pressure in the tubes to allow conirnunication between the tubes While the pressures in the tubes are maintained within a predetermined differential range of pressures.

11. In combination with a vehicle having multiple tire wheels, a signalling device comprising a vibratory diaphragm, a member having therein a rst passageway for delivering gas under pressure to said diaphragm, and a second larger passageway allowing escape of the air delivered against the diaphragm through the rst passageway whereby flow of air from the rst passageway into the second passageway will cause the diaphragm to vibrate, a separate chamber communicating with each associated tire tube, a diaphragm valve in the chamber communicating with the first passageway and the associated tube, the pressure in the chamber and the tube normally maintaining said valve closed and means for exhausting gas from said chamber when the pressure in the tube falls below a predetermined minimum, said valve opening when the gas exhausts from said chamber, Whereby gas will ow from said associated tire tube through said valve to the diaphragm to vibrate it at audible frequency.

12. The combination set forth in claim 11, comprising a member having a passage therein connecting each chamber with its associated tire tube, and a manually actuated valve communicating with the chamber and said passage for allowing gas to ow from said tube to said chamber.

PIERRE MARCEL BOURBON. 

